Rosemary hedge dead/dying - do I need to replace the soil once I have dug it up??

Hedge has been growing magnificently for about 5 years, the nit started to droop, and now about half of the plants are just wood, and the remaining ones are withering.

There could be a few answers as to why ( I have been googling this), and nothing seems directly relevant. This phenomenon has commenced about the same time as the mass invasion by mini-strawerry 'ground cover' making it's way around the soil and parts of the lawn - which I didn't mind at first, but now am thinking it could be associated with the death of rosemary??

Sooo...once I dig up what's left of the hedge, ( and get rid of stawberries) should I be replacing the soil, or is this a bit OTT??

thank you for all of this. I am tending toward a fungal infection - the plants are dying 'in a row' rather than simultaneously, which prob. rules out root rot ( as they would all be being affected at the same time) and any other environmental factors. Also it has been growing vigorously for years, and then suddenly 'bam'!!

sad day tomorrow, then. digging up the hedge - it's about 4 feet high - and I will check for weevils, tho' I read the little buggers are nocturnal AND good at camuflage.

I bet it's rosemary bettle... I've just lost my big hedge to the little blighters.They look like black, iridescent ladybirds.you can get a spray to kill them, but my friend swears by spreading a white sheet under the plant, shaking vigoursly and they all fall out. you need to squash or burn them <eek>

Have dug up the now-very woody stems and roots, and dug over the soil wit hno sign of the named suspects. Some of the hedge was still sprouting new shoots, so have taken LOTS of cuttings for propagating, as have my next door neighbours.....

so it's propagating in pots over summer, and when they are big and bonny next spring, they go back in.. Front of house looks oddly naked.thanks again for assistances.